The invention relates generally to welding systems, and particularly to control of a welding system for gas-metal arc welding (GMAW), also known as metal inert gas (MIG) welding systems.
Arc welding systems generally comprise a power supply that applies electrical current to an electrode so as to pass an arc between the electrode and a workpiece, thereby heating the electrode and the workpiece to create a weld. In many systems, such as gas metal arc welding systems (GMAW), the electrode consists of a wire which is advanced through a welding torch. As the electrode is heated by the arc, the electrode melts and is joined to molten metal of the work piece to form the weld.
Advanced forms of MIG welding are based upon generation of pulsed power in the welding power supply, which may be known as pulsed gas metal arc welding (GMAW-P). That is, various pulsed regimes may be carried out in which current pulses and/or voltage pulses are commanded by the power supply control circuitry to regulate the formation and deposition of metal droplets from the welding wire, to sustain a desired heating and cooling profile of the weld pool, to control shorting between the wire and the weld pool, and so forth.
By controlling the supply of voltage and current to the electrode, a GMAW system may control the manner in which the electrode is melted and deposited by the arc. Controlling the arc length between the electrode and the workpiece may affect the energy applied and/or how the electrode is deposited by the arc. Some GMAW systems may attempt to maintain a constant arc length by controlling the weld voltage supplied to the torch. However, an arc voltage across the arc length may be only a part of the weld voltage between the torch and the workpiece.